Single database for multiple shops

Use ActsAsTenant as Multi-tenancy for shops

See below files:
- app/controllers/concern/multi_tenancy.rb
- app/models/application_record.rb
- app/models/shop.rb

An initializer can be created to control option in ActsAsTenant.
config/initializers/acts_as_tenant.rb
require 'acts_as_tenant/sidekiq'
ActsAsTenant.configure do |config|
  config.require_tenant = false # true
end

more details: https://github.com/ErwinM/acts_as_tenant

app/uploaders/product_image_uploader.rb

@@ -20,11 +20,11 @@ class ProductImageUploader < CarrierWave::Uploader::Base
   end
 
   def filename
-    if Shop.first.shop_code.nil?
-      "#{original_filename}" if original_filename.present? 
+    if Shop.current_shop.shop_code.nil?
+      "#{original_filename}" if original_filename.present?
     else
-      "#{Shop.first.shop_code}_#{original_filename}" if original_filename.present? 
-    end    
+      "#{Shop.current_shop.shop_code}_#{original_filename}" if original_filename.present?
+    end
   end
 
   # def cache_dir